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Applications of
vironmental
Adsorption,
2.4 En Ion Exchange, and Catalysis 51
v
nitrogen oxides by oer 70%. T about one-third of the world market for catalysts
oday
,
involves environmental catalysis.
Generally, catalysts are called into action to eliminate emissions from mobile (cars) and
stationary (industry) sources, to take part in liquid and solid waste treatment, and con-
tribute to the effort to reduce volatile organic compounds and gases that pose major en vi-
ronmental problems such as photochemical smog and (at a global leel) the greenhouse v
effect.
The use of catalysts for exploiting reneable energy sources, producing clean fuels in
w
refineries, and minimizing the by-product formation in industry also fall within the def i-
nition of environmental catalysis. In the future, the continuous effort to control transport
emissions, improe indoor air quality and decontaminate polluted water and soil will fur- , v
ther boost catalytic technology catalysts will continue to be a valuable asset in
All in all,
.
the effort to protect human health, the natural environment, and the existence of life on
Earth.
we
v
er
,
v
There are, ho some distinctie differences between the environmental and the
other aspects of catalysis. First, the feed and operation conditions of environmental cata-
lysts cannot be changed in order to increase conersion or selecti as commonly done vity v ,
for chemical production catalysts. Second, environmental catalysis has a role to play not
ut also in emission control (auto,
only in industrial processes, b ship, and flight emissions),
and een in our daily life (water purifiers). Consequently the concept of en vironmental
v
,
catalysis is vital for a sustainable future. Last but not least, environmental catalysts often
operate in more extreme conditions than catalysts in chemical production. There are also
v
ehicles,
cases, such as automotie v where they hae to operate eficiently for a continu- f
v
ously varying feed flow rate and composition.
The most important catalytic production processes are the follo wing:
• the Haber process for ammonia synthesis
• steam reforming of hydrocarbons to produce synthesis gas
• methanol synthesis
• Fischer–Tropsch synthesis
• hydrogenation/dehydrogenation of organic compounds,
• sulfuric acid production
• nitric acid production
• maleic anhydride production
• petroleum refining and processing

In the area of environmental application of catalysis, the most important processes are

• catalytic reduction of NO x
• catalytic oxidation of SO 2
• catalytic oxidation of CO, V and hydrocarbons OC,
• catalytic denitrification of drinking w ater
• catalytic oxidation of persistent organic pollutants in w ater w aste